Synchronous motor



April v16, 1929- H. .1.' BLAKESLE 1,709,055

SYNCHRONOUS MOTOR Filed Sept. 16. 1927 2 Sheets-Sheet Patented Apr. 16, 1929.

UNI-TED STATES y HENRY J. BLAKESLEE, OF WEST 'HARTFORD, CONNECTICUT.

SYN CHRONOUS MOTOR.

Application filed September 16, 1927. Serial No. 219,916.

This invention relates to an instrument which is designed to be connected in an electrical circuit and is actuated in synchronism with the electrical cycles in the line and which is particularly adapt-ed, to be embodied 1n an apparatus for measuring short intervals ot time, for instance, adevice for test-ing the action of relays.

The object of the invention is to provide a simple, portable, accurate, quick acting 1nst-rument which is convenient to handle and read, and is adapted to act in synchronism with the source ot pow'er.

In attaining this end there is arranged in a casing asynchronous oscillating electromagnetic motor which, in the embodiment of the invention illustrated, is connected with a train of gears having indicating pointers, by a ratchet and pawl mechanism arranged between the motive element of the motor and the gear train,as more particularly hereinafter described.

In the accompanying drawings Figure 1 shows a tace view of a cycle counter which is operated by mechanism that embodiesthis invention.

Figure 2 shows a front elevation of the mechanism with the casing removed.

Figure 3 shows a vertical section of the structure.

Figure 4 shows a rear elevation of the mechanism. 2

Figure 5 vshows la section of the motor lwhich is responsive to the electrical impulses and which drives the counting gears.

Figure 6 shows a rear view of the motor.

The casing 1 of the instrument is desirably made of insulating material with a cover 2 in the face of which is a. window 3. Fastened in the casing is a permanent magnet 4 with arc shaped pole pieces 5. Fitted within the pole pieces ot the magnet is an induction coil 6. '.lhis coil is held bet-wecn'plate 7 that are on each side and are secured together by screws 8. One terminal of the coil winding is connected by a conductor 9 with the inner end of a binding post 10 that extends through the cover and has a binding nut 11 on the outside.v The other terminal of the coil winding is connected by a conductor 12 with the inner end of a binding post 13 that on the outside of the cover has a binding nut 14. In the arrangement illustrated one line wire 15`is shown as connected with the binding post 10 and the other line wire 16 is shown as connected With the binding post 17 that on the front of the cover has a binding nut 18. Connected between the binding posts 13 and 17 is a resistance 19 protected by a casing 20.

Rot-atably supported by the plates 7 is an arbor 21 that extends through the center of the motor coil. Fastened to this arbor are angular armature plates 22 and 23,-the former extending back of the coil and toward the front at one edge and the latter extending in front ot and toward the rear at the diametri- 'cally opposite edge of the coil. Turning loosely on the front end otl the arbor are a pinion 24 and ratchet wheel 25. Extending forwardly from the armature plate 23 is a stud 2G and adjustably fastened to this stud a block 27 which has a pawl 28 that is held 1n engagement with the teeth of the ratchet wheel by a spring 29 for the purpose of turning the ratchet wheel forward. A pawl 30 1s held by a springA 31 in engagement with the teeth of the ratchet wheel for preventing 1t from turning backward. Opposingsprings 32 are arranged between adjustable plates and t-he stud 26 to retain the armature plates in normal' position. These springs compensate each other under temperature changes so that the ends of the armature in rest position Will remain constant opposite the gaps between the pole pieces of the magnet.

In the counting device illustrated there. is engaged with the pinion 24 a pinion 34 mesh- -ing with which is a gear 35 engaged with a gear 36. Fastened to the gear 36 is a pinion 37 which meshes with the gear 38. The arbor 39 of the gear 35 extends through the cover and in front of the graduated dial 41 bears a pointer 42 While the arbor 40 of the gear 38 extends through the cover and has a pointer 43 in front of the' graduated dial 44. In the particular device shown the gearing ratio is such that the pointer 42 makes one revolution for each 6() cycles, or one revolution per second it' the instrument is connected with a 60 cycle line, and the pointer 43 makes one revolution to each 10 revolutions ofthe pointer 42. On the front end of the arbor 39 is a button 45, and on the front ot the end of the arbor 40 is a button 46, these buttons being provided for setting the point-ers 42 and 43.

lVhen this instrument is connected in a circuit current passing through the coil oscillates the armature synchronously with the electrical impulses, or cycles of alternation, and the oscillations of the armature are transmitted through the ratchet and pawl mechanism to the gear train which turns the pointers. Thus the cycles may be counted by the movement of the pointers. lV hen the circuit is closed the motor armature instantly starts oscillating and when the current is cut oil' the armature immediately stops, thus the cycles may be counted'in short intervals of time, or reversely, knowing the number of cycles per second of the current, the time ot an action, such as the time action of a relay, may be accurately read by the positions of the pointers over the dials. The motor armature turns the gear train directly and positively and as there are no brushes to interfere with the action ot' the armature it will start and stop quickly so that close readings may he maile.

The synchronous motor shown and described may he employed for operating other mechanism than the counting gears illustrated.

The invention claimed is:

1. A synchronous motor comprising a permanent magnet having arc shaped pole pieces, a stationary circular coil located between the pole pieces ol? the magnet, an oscillating armature suhject to electrical impulses in said coil, said arlnature passing through the center of said coil and the ends ot' said armature em-4 bracing the exterior' ot' said are shaped pole pieces, and two springs connected to said a1'- lnature and tensioned in opposite directions whereby changes in temperature will equally affect them and the position of rest of said armature Will be the same at all temperatures.

2. A synchronous motor comprising a permanent magnet having arc-shaped pole piecesl with a circular opening between them, a stationary circular coil closely tted in said opening and having its axis concentric with the axis of thel pole pieces, and an oscillatory armature with its axis of oscillation concentric with the axis of said coil and pole pieces,

tric with the axis o'l said coil and pole pieces,

said armature having a terminal extending i outside of the pole pieces and adapted to swing back and i'orth across one space between the terminals ofthe pole pieces and having a terminal extending outside ot' the pole pieces and adapted to swing back and l'orlh across the other space between the terminals of the pole pieces.

4. A synchronous motor comprising a permanent magnet having arc-shaped pole pieces with a circular opening between them, a .stationary circular coil closely fitted in said opening and having its axis concentric with the axis ot the pole pieces, an oscillatory armature with its axis of oscillation lconcentric with the axis of said coil and pole pieces, said armature having a terminal extending outside of the pole pieces and adapted to swing back and forth across one space between the terminals of the pole pieces and having a terminal extending outside of the pole pieces and adapted to swing back and forth acrossthe other space between the terminals of the lpole pieces, and a spring connected to normally retain the' armature terminals opposite 'the spaces bet-Ween the pole piece terminals.

HENRY J. BLAKESLEE. 

